This invention relates to a rodlike antenna device used in a portable radio device (e.g. radio transceiver) or the like, which antenna device is withdrawable from and receivable in a body of the radio device.
One conventional antenna device of the type described is shown in FIG. 3 which is a cross-sectional view of a portion of this antenna device. This antenna device comprises a rodlike antenna 51 covered with a rodlike antenna cover 52, and a helix antenna 53 covered with a resin cap 54. The rodlike antenna 51 is electrically conductively connected at its distal end to the helix antenna 53, and the rodlike antenna cover 52 is integral with the cap 54.
The rodlike antenna cover 52 is mounted on a body (not shown) of a portable radio device in such a manner that the cover 52 is withdrawable from and receivable in the body. When the rodlike cover 52 is withdrawn into an extended position, radio waves are transmitted and received through the helix antenna 53 and the rodlike antenna 51. When the rodlike cover 52 is received in the body, that is, disposed in a retracted position, the rodlike antenna 51 is disposed in the body while the cap 54 is exposed, and therefore in this condition radio waves are transmitted and received mainly through the helix antenna 53 projected from the body.
In the above conventional antenna device, however, when the antenna is in the retracted or received condition, the rodlike antenna 51 received in the body is electrically communicated to the helix antenna 53 projected from the body, which results in a problem that antenna characteristics of the helix antenna are degraded.